The sympathetic nervous system uses the catecholamine norepinephrine to regulate blood pressure and regional circulation. We will use existing radioenzymatic methods to measure norepinephrine and dopamine-Beta-hydroxylase and adapt other radioenzymatic techniques to measure dopamine and epinephrine in blood and cerebrospinal fluid. These techniques will be used to study the sympathetic nervous defect in postural hypotension that is caused by disease or antihypertensive drugs so that plasma catecholamine levels can be used to diagnose the cause of these disorders. The response of plasma catecholamines to various antihypertensive drugs will be measured to provide a rational basis for therapy with combinations of these drugs. People exposed to the metal lead excrete abnormally high levels of catecholamine metabolites and have an increased incidence of hypertension. We will determine if patients with elevated lead levels have increased circulating catecholamines and increased blood pressure to determine if lead is a significant etiologic agent in the development of hypertension. Cardiac patients with angina pectoris or cardiac arrythmias frequently respond favorably to Beta-blocking drugs such as propranolol. We will measure circulating catecholamines in these patients to determine: a) If patients with angina or arrythmias have increased levels of catecholamines, and b) if catecholamine levels can be used to predict which patients are likely to respond to catecholamine receptor blockers such as propranolol.